Despite gloom on the high street and anxiety about the digital future, the UK's presses have been proving over the last week that their cheque books are still there – for the right titles. A host of high-rolling auctions for big new books have been taking place behind closed doors in the run-up to the book fair, with many stretching into six figures as publishers battle it out for supremacy.

At Orion, staff were rejoicing over the acquisition of the debut novel from Iranian/American author Sahar Delijani, Children of the Jacaranda Tree, for a sum "well into six figures". "It's a sensational book," said Jon Wood, publishing director. "We bought it last night … People were bidding huge amounts of money."

Delijani's first novel is composed of seven different narratives linked by one event: the imprisonment and execution of political activists in the summer of 1988 in Iran, from a baby born in Tehran's prison to a man executed that year. "She's drawn them from stories told to her by her parents [who were imprisoned themselves]," said Wood. "The writing is incredibly powerful and incredibly sad – it's obvious she knows all about it."

Jonny Geller, literary agent at Curtis Brown, tied up a six-figure auction for a spy novel by former CIA operative turned novelist Jason Matthews late on Friday. Simon & Schuster saw off competition from five other publishers to win Treason, in which a honey trap agent trained in Putin's Russia gets involved with a CIA agent looking after a mole in the Russian secret service. A five-way auction stretching into six figures was also conducted for a trilogy of historical novels by debut novelist Liz Freemantle, with Penguin imprint Michael Joseph set to publish the first, Queen's Gambit, telling the story of Henry VIII's sixth wife Katherine Parr, next summer. And at HarperCollins, publishing director Katie Espiner won another auction with a six-figure bid for Rosie Garland's debut The Palace of Curiosities.

"It's felt like an even busier run-up than usual to LBF this year – there seems to have been a new auction running every other day," said Espiner. "We'd just won an 11-publisher auction for another debut, Nathan Filer's Where the Moon Isn't, when Rosie's novel came in. As Jonny Geller observed on Twitter, "accusing an agent of 'hype' just before London book fair is like complaining that the Pope should not be such a stickler for tradition". The pitch for The Palace of Curiosities made it sound so amazing – a new Angela Carter – that I worried it couldn't possibly live up to it. I was so wrong. It has one of the best opening scenes I've read for years. I was so hooked that I ended up finishing it on my phone, and it was still wonderful – clever, dark, funny and utterly heartbreaking. It's incredibly special and has what we're all looking for, that rare combination of truly brilliant storytelling with characters you really care about."

It's not only new names commanding attention at this year's London Book Fair, a three-day event attended by over 24,000 publishing professionals from around the world, where rights in the hottest new books are bought and sold. Literary novelist William Boyd's take on the James Bond legend, announced last week, has already been sold to publishers in Germany and France, while agent Deborah Rogers has been signing deals left, right and centre for McEwan's latest. Set in 1972, Sweet Tooth is the story of Serena Frome, the daughter of an Anglican bishop, as she enters the intelligence service and falls for a promising young writer while on a mission. Out in the UK this summer, Rogers has already sold it to 14 other countries and promises this is "just the beginning". "It's only just come in and it's moving very quickly," she said. "A new Ian is always a very exciting moment."

Geller said the rights market "seems much more vibrant than last year – publishers have woken up". Wood agreed. "The money is there for the right books and publishers are keen to spend their money on the right books," he said. "People are spending more per title, but buying less overall, which is why auctions are going into overdrive."